Field of the Invention
The present disclosure generally relates to displays and, more particularly, to a display apparatus and a method for controlling a display apparatus.
Description of the Related Art
Conventionally, a liquid crystal projector using a liquid crystal panel is known as a display apparatus. When a display apparatus using a display panel (a liquid crystal panel) displays a moving image, motion blur occurs, in which the contour of a moving portion is displayed in a blurred manner. Examples of the cause of the motion blur include the response characteristics of the liquid crystal panel. For example, when an nth frame is displayed, it takes time for liquid crystals to change from the state of having the target transmittance, based on image data of an n−1th frame, of the liquid crystal panel to the state of having the target transmittance, based on image data of the next nth frame, of the liquid crystal panel. The liquid crystals are in an unstable state during the period until the proportion of the actual transmittance to the target transmittance of the liquid crystal panel, which is determined based on the image data to be displayed, is equal to or greater than a predetermined value. The light irradiating the liquid crystal panel during this period is visible to a user. This can cause the motion blur.
As a method for reducing such motion blur, Japanese Patent Application Laid-Open No. 2007-148444 discusses a method for, in a liquid crystal display, partially controlling lighting of a light source based on information about the start of scanning a liquid crystal panel and the response characteristics of liquid crystals. Then, the motion blur is removed by the method turning off a part of the light source corresponding to an area of the liquid crystal panel where the proportion of the actual transmittance to the target transmittance of the liquid crystal panel, which is determined based on the image data to be displayed is less than a predetermined value, thereby removing motion blur.
Also in a liquid crystal projector, it is possible to partially control a light source by placing a plurality of light sources so as to correspond to a plurality of divided areas of a liquid crystal panel. However, it is not enough for the liquid crystal projector to merely employ the conventional technique for removing the motion blur in a liquid crystal display. The liquid crystal projector has different display modes, such as a normal projection mode, where the liquid crystal projector is used in a state of being placed on a desk or the like, and a hanging projection mode, where an image is projected with the main body of the liquid crystal projector fixed upside down to a ceiling or the like. Thus, in the case of the liquid crystal projector, it is necessary to take into account the relationship between a scanning direction of the display panel and control of the plurality of light sources in the normal projection mode or the hanging projection mode, which does not exist in the case of a conventional liquid crystal display.